Peridinium

Introduction

Peridinium is a large genus of small to medium sized
dinoflagellates, some but not all of which are photosynthetic.
Nonphotosynthetic species are phagotrophic or osmotrophic.

Species
occur in freshwater and marine planktonic habitats worldwide. At least a
few photosynthetic species may form significant blooms ("red tides").
Some of these blooms are associated with nuisance odors and fish kills,
although the most devastating "red tide" dinoflagellates belong to other
genera.

Photosynthetic species in the genus Peridinium,
and species in closely-related genera that are still treated as species of
Peridinium by many workers, are frequently used as experimental
organisms in cell biology research, especially in the areas of nuclear
structure and function, circadian rhythms, and endosymbiosis.

The
unique structural and molecular features of Peridinium and its
relatives have prompted much speculation on the evolutionary history of
dinoflagellates. Not long ago, this group was believed to be among the
most ancient of the extant eukaryotic lineages. Evidence presently
suggests, however, that dinoflagellates are a derived group, most closely
related to the ciliates and the apicomplexan sporozoans.

Postulated global
eukaryote phylogeny based on presence or (ancestral) absence of
mitochondria, and shape of mitochondrial cristae. Peridinium
belongs to the tubular clade.

Postulated phylogenetic position of Peridinium, inferred from
molecular and morphological data.
Branch lengths are arbitrary and do not reflect phylogenetic distance.